High-Performance Flip Chip Bonding Mechanism Study with Laser Assisted Bonding

Recent advanced flip chip ball grid array (FCBGA) packages require high input/output (I/O) counts, fine-pitch bumps and large/thin package substrates. One of the key hurdles to accommodate these requirements is the flip chip bonding process. Therefore, advanced flip chip bonding technologies are continuously being developed and one of the promising solutions is laser assisted bonding (LAB) technology. The key advantage of LAB is its extremely short bonding time (less than 1 sec) with a localized heating area which provides low thermal and mechanical stresses.In this study, two bonding profiles of "time fixed" and "power fixed" are tested using 15.2 x 15-mm ² FCBGA test vehicles with three difference die thicknesses. Wetting sequences of the solder joints are inspected with time interval of 100 ms. Solder bump interconnections are analyzed by cross section and reliability tests are performed. LAB is also compared with thermocompression bonding (TCB) for process and solder joint characteristics.